Fan construction



Aug. 7,1945.` w. R. BoNHAM y 2,381,567

FAN CONSTRUCTION Filed April 4, 1944 :EM-M

' INVENTOR.

WALTER r?. 15o/114A m.

Patented Aug. 7, 1945 UNITED sTATEs PATENT OFFICE FAN CONSTRUCTION waiter n. Bonham, Pale Ain, cant.

Application April 4, 1944, Serial No. 529,529

(ci. 23o-271) 3 Claims.

This invention relates generally to the cooling structures of internal combustion engines, particularly those of the liquid cooled type, in which a draft of air is forced over a heat radiating surface by means of a fan. In the conventional automotive installations, a cooling fan is situated behind the radiator and driven` by a belt or other means from the engine crank shaft. Devices of this character `are responsive to but one condition, namely, the speed of the engine. However, the function of the fan is simply to draw air over the heat radiating surface and since both the fan and the heat radiating surface must be designed to take care of maximum conditions of heat dissipation, there are many times in the operation of the vehicle when operation of the fan is unnecessary. However, in the conventional installation, the fan operates whether it is necessary or not. Not only does this cause unnecessary wear but in addition requires considerable power, particularly at high speeds. As a matter of fact, the power absorbed to drive the fan alone at high speed is probably suicient to drive the entire vehicle at low speed.

It is an object of the present invention to provide means for operating the fan only at such time as it is necessary to do so.

A further object of the present invention is to provide a means of conserving Power which would otherwise be wasted in driving the fan when it is unnecessary that the fan be operated.

Other objects and advantages of the present invention will appear from the following description taken in conjunction with the accompanying drawing, in which:

Fig. 1 is a cross-sectional detail showing a fan mounting embodying my invention, and V Fig. 2 is a cross-sectional elevation taken along the line 2-2 of Fig. 1.

Fig. 3 is a cross-sectional elevational .detail as illustrated in Fig. 1 showing the fan in nonoperating condition.

In its preferred form the fan assembly herein described includes a cooling fan which is suitably driven through a clutch mechanism which may be rendered effective or ineffective by the action of a. thermostatic device.

In the device shown in Fig. 1 there is provided a Zfan assembly support I0 which is connected to the vehicle engine (not shown herein) and which is located some distance to the rear of a radiator core I I which is suitably connected to the cooling system of the engine and which acts as a-dissipator of the heat therefrom. The entire fan assembly is on the lee side of radiator Il and is subjected to air which is passed through the radiator core and has been heated thereby. The fan assembly support Ill is provided with a cylindrical bore in which there is rotatably mounted a shaft I2. Shaft I2 may be secured in any conventional manner against longitudinal movement with respect to fan assembly support I0.

Mounted upon shaft I2 is a clutch of any suitable type for this purpose, but preferably of the character shown in my Patent No. 2,052,961, issued September 1, 1936. This clutch is of the helical spring type and includes a hub 20 which is secured by means of shrinking, welding, or any other suitable method to rotatable shaft I2. Hub 20 is likewise secured by spot welding or otherwise to a conventional fan pulley 2| with which is engaged a driving belt connected to the crank shaft of the engine (not shown) in the customary fashion.

Rotatably mounted upon shaft I2 by means of anti-friction roller bearings 25, for example, there is a circumferential shell 26.` Shell 26 is provided with a radially extending ilange 21 to which a conventional fan 28 is secured by means of bolts 29 or any other suitable connection. As shown, fan 28 consists of members 30 and 3l set at right angles to each other and which Overlie each other at their intersections. As shown in Fig. 1 members 30 and 3l are spaced from the forward face of rotatable shell 26 in such a manner that a radial chamber is created therebetween. A portion of members 30 and 3i at their intersection is cut away providing circular orifice 36 by whichv chamber 35 is placed in communication with the air which has passed through radiator core II. Shell- 26 may be secured against longitudinal movement in any suitable manner.

Hub 20 is provided with a convex cylindrical surface 40 which is in alignment with a similar convex cylindrical surface 4I on shell 26. On that portion of surface 40 remote from shell 26 there is provided a peripheral groove 42, the purpose of which will be described hereafter.

As described, therefore, it is obvious that pulley 2|, shaft I2, and hub 20 will rotate as one and constitute a driving unit. It is also clear that shell 26 and fan 28 rotate as one and constitute a driven unit.

In order to couple, when desired, the otherwise freely rotatable shell 26 to driving hub 40, there is preferably provided a helical member 43 which conveniently takes the form of a coil spring. The

spring denes a concave cylindrical surface 44 which is adjacent to and overlies the respective convex cylindrical surfaces 40 and 4I on the driving hub 20 and the driven shell 26 and is parallel thereto since the axis of the spring is 5 convex cylindrical surfaces 40 and 4|, serving 15 to couple them securely and transmit the rotation of the driving hub to the driven shell 26.

In order to control the means for energizing the clutch, I utilize the temperature of the air just after it has emerged from the radiator core 20 Il. To this end, there is mounted within chamber 35 a thermostatic mechanism comprising a bimetallic snap disc 46 of conventional type.

Bimetallic disc 46 is suitably mounted within chamber 35 and secured to a lever 41 one end of 25 which forms a shoe 48 which passes through orice 49 in shell 26 and overlies a portion of helical spring 43, as shown in Fig. 1. This thermostatic mechanism is responsive to critical tem` peratures of the air flowing through the radiator core, absorbs heat therefrom and is adapted to operate at a predetermined temperature.

That end of lever 41 remote from turned up shoe portion 48 is formed generally in a loop 50 as shown in Fig. 1, forming a pivot for lever 41, in order that any movement of bimetallic plate 46 will be transmitted to shoe 48.

,Operation of the device may briefly be described as follows: Assuming that the air drawn through radiator core il is less than a predetermined@ temperature, bimetallic disc llt will be substantially fiat as shown in Fig. 4 and shoe 48 will be withdrawn from the position shown in Fig. 1 at which it overlies a portion of helical spring d3.

In that event rotation of fan pulley 2l, hub 26, 45

and shaft l2 may be maintained free of fan 26 and its complementary parts. Rotation of the driving parts, that is fan pulley 2l, hub 26 and shaft l2 requires relatively little power and as a mattei' of fact is necessary in the conventional 5o.

design for the purpose of driving the generator, water pump, etc. However, continued operation of the engine will cause the cooling medium to become warm and ultimately the air passing through radiator core Il will absorb considerable 55 heat. When the air flowing through the radiator core and having absorbed heat therefrom reaches a predetermined temperature, the thermostatic element composed of bimetallic snap disc 46 will respond thereto. Snap disc 46 will then assume 60 the position shown in Fig. 1 in which event shoe 48 of lever 41 will overlie a portion of helical spring 43. Rotation of the driving elements including helical spring 43 will ultimately bring shoe 48 and upstanding stud 45 into engagement 65 at which time the engagement of shoe 48 and upstanding stud 45vdraws the inner concave surface of helical spring 43 snugly against the aligned convex cylindrical surfaces and 4I thereby coupling them securely. This accomplished, the '(0 driven fan unit composed of fan 28 and shell 26 of spring 43 within slot 42.

will be securely coupled to the driving elements and will rotate therewith.

Should the air striking bimetallic thermostatic plate 46 fall below the predetermined temperature heretofore mentioned, disc 46 will snap to relatively flat or planor position withdrawing shoe 48 from the position overlying helical spring 43. In that event helical spring 43 is free to uno wind whereby concave surface 44 will withdraw from contact with aligned convex surfaces 40 and 4I and driving hub 20 and driven shell 26 will be disengaged. In accordance with this arrangement, the cooling effect of the fan is responsive to the cooling eifect required by the engine, and the objects and advantages heretofore specified are attained.

It should be noted that there is no abrupt clutching with the device herein illustrated. Obviously, the immediate interconnection between the stationary part of the engine "and a rapidly revolving element is highly undesirable. The degree of rapidity with which clutching action takes place may be determined by the frictional contact If the engagement is heavy the connection will be more rapid than if the engagement were light.

I claim:

l. In a fan construction of the character described, a driving unit composed of a fan pulley, a hub, and a rotatable shaft, a driven unit composed of a fan and a shell, said driving and driven units being coaxially aligned, said driving hub having a convex cylindrical surface, said driven shell having a convex cylindrical surface, said surfaces being aligned, a helical spring adapted to overlie said surfaces in declutched position and to engage said surfaces when in clutch position, and thermally responsive means mounted on said driven unit for urging said spring to full clutch or full declutched position.

2. In a fan construction of the character described, a driving unit composed of a fan pulley, a hub, and a rotatable shaft, a driven unit composed of a fan and a shell, said driving and driven units being coaxially aligned, said driving hub having a convex cylindrical surface, said driven shell having a convex cylindrical surface, said surface being aligned, a helical spring adapted to overlie said surfaces in declutched position and to engage said surfaces when in clutched posi tion, thermally responsive means mounted on said driven unit for rapidly coupling and uncoupling said driving and driven units whereby said driving and driven units are in either full clutched or full declutched position.

3. In a fan assembly of the character described, a pulley adapted to drive a driving hub, a fan adapted to be driven by a, driven shell, said hub and said shell having aligned cylindrical surfaces, a helical spring member adapted to contact both of said surfaces, means or firmly relating said helical member to said liub, thermally responsive means for rapidly urging said helical member into contact with both of said surfaces, the end of said helical member remote from said energizing means being in frictional engagement with said driving hub whereby said helical means absorbs the first shock of the clutching action of said helical member and said shell and hub.

WALTER R. BONHAM. 

